1999 neon making a loud screeching noise under hood passenger side

Does it sound like backfiring or knocking or squealing/screeching or what ?

Sounds like you may have a bad front wheel bearing.

The blower is located under the passenger side however, the screech in the engine are is most likely a lose belt. Tighten or replace your belts and teh sound should go away.

The high pitch sound may come from the brake pads as metal parts hit the disc to signal the owner that it needs change. The metal parts gets exposed when the pads have worn out. The brake also has a hub to cover the disc. See if the metal plate is hitting it but this issue would appear when the wheels are in motion. Check if it is the belts, have the tension checked out. Other than that the bearings are the other items on your wheel that could cause a high pitched sound when you car is in motion.

How about checking the fan belts, they may need adjusting or replacing.

does it do that noise when is running or when u start it?

Does it make this noise when you turn corners.

the main motor is on the passenger side. there is a link between the to that operates the driver side wiper. the link has to be replaced.. what i am finding is that you have to buy the whole wiper kit which is approx.70 dollars instead of just buying the link or gromet.

The only four rotating items under the hood are
engine
power steering pump
A/C compressor
and smog emission pump.
==== I would check the fluid level on the power steering first. Check for pink fluid leak on the ground,
==== Check the A/C system with the wheel turn to one side and APPLY ALL LOADS.
Example: high beam on,A/C max,radio on and deforster on.
This will give you system a stress test.
All eyes on the pully and locate to part that generate the loud screeching noise.
My bet is on the power steering pump.

Please post more info on the comment window.
I will follow up on it.

I'm guessing that you Expedition has been making this noise probably since you've had it? Even if it hasn't, I think I can bring you some comfort. If you could pinpoint where the noise was coming from under the hood, would you say that it's somewhere over on the passenger side? My dad owns a 1998 Ford Eddie Bauer Expedition, and we noticed a loud noise with the same habits as what you're describing. Come to find out, there is an air compressor under the hood, I can't remember exactly what it's for, but the sound that I believe you're hearing is the compressor filling up with air and then shutting off once the proper amount of pressure is reached. You might try popping the hood to try to locate the exact place that it's coming from, but I can tell you that it's probably a 99% chance that when you find your noise, you'll find the compressor I'm referring to. Hope this proves to solve your issue and helps to ease your worries. Have a wonderful evening!

James